Insulated electric conductor splice



Sept. 29, 1959 R. G. D'ASCOLI 2,906,810

INSULATED ELECTRIC CONDUCTOR SPLICE Filed Feb. 15, 1956 FIG. I

INVENTOR RALPH GREGORY D'ASCOLI ATTORNEYS United States Patent INSULATEDELECTRIC CONDUCTOR SPLICE Ralph G. DAscoli, Yonkers, N.Y., assignor toAnaconda Wire and Cable Company, a corporation of Delaware ApplicationFebruary 15, 1956, Serial No. 565,656

7 Claims. (Cl. 174-87) This invention relates to the splicing ofinsulated electrio conductors, and more particularly to the splicing ofan insulated bridge conductor to an insulated through conductor, as forexample in telephone cables. The invention aims to provide certainimprovements in such splices and Water-proof enclosures therefor.

The splice of the invention comprises essentially a cylindrical capsulehaving one end closed and the other end open, a cylindrical plug servingas a separator, plunger and stopper securely fitted within the capsulenear its open end, and a mass of plastic waterproof insulating materialfilling the capsule and surrounding and embedding the twisted strippedends of the spliced conductors. The unstripped end portions of thespliced conductors extend through circumferentially spaced peripheralgrooves along the cylindrical surface of the plug to a short distancewithin the capsule, and preferably converge abruptly from the grooves tothe twisted stripped ends of the conductors, with the space between theinner face of the plug and the adjacent twisted stripped ends of theconductors being about one-quarter of an inch.

The invention further contemplates a novel waterproof enclosure for aplurality of splices of the invention, as for example where individualinsulated conductors of a through telephone cable are spliced toindividual insulated conductors of a bridge cable. The several splicesare covered with suitable insulating material, such as a wrapping offriction tape, and enclosed within a cylindrical tube of an insulatingplastic closed at its opposite ends by cylindrical plastic collars eachextending a short distance beyond the end of the tube. Each of thecollars is made of mating half cylinders bolted or otherwise suitablysecured together and having a longitudinal opening through which thethrough cable extends. One of the collars has another longitudinalopening through which the bridge cable extends. The tube and extendingends of the collar are surrounded by a water-proofing compound.

The foregoing and other novel features of the invention will be betterunderstood from the following description taken in conjunction with theaccompanying drawing, in which Fig. 1 is a sectional view of aninsulated splice embodying the invention,

Fig. 2 is a perspective view of the closing plug of the insulatedsplice,

Fig. 3 is a sectional view of a waterproof cable junc tion for severalsplices of the invention, and

Fig. 4 is a perspective view of one of the mating halves of anend-closure collar for the cable junction of Fig. 3.

In general, the insulated splice of the invention (Fig. 1) comprises acylindrical capsule 5, a cylindrical closing plug 6, and the twistedstripped ends 7 of the spliced conductors embedded in a mass 8 ofplastic waterproof insulating material. For purposes of illustration,the drawings show an insulated'bridge conductor 9 spliced to aninsulated through conductor 10-10, which has 2,906,810 Patented Sept.29, 1959 been cut to provide two end portions for stripping andsplicing. The insulated conductors 9 and 10-10 are positioned inperipheral grooves 11 extending longitudinally along the cylindricalsurface of the plug 6 and circumferentially spaced apart.

The position of the conductors 9 and 1010' in the grooves 11 is suchthat the insulating sheaths of the conductors extend a short distancebeyond the inner face or end of the plug 6 with the twisted splice 7close to this end of the plug. Advantageously, the short insulatedportions of the conductors beyond the inner end of the plug are taut andconverge abruptly from the grooves 11 to the splice 7.

The capsule 5 is preferably made of an insulating plastic, while theplug 6 may be made of plastic, wood, metal, rubber or other suitablematerial. Very satisfactory practical results have been achieved withcapsules and plugs made of cellulose acetate butyrate and particularlywith Tenite II a cellulose acetate butyrate product marketed byTennessee Eastman Co. The plastic insulating material 8 is preferablythe putty-like plastic composition described and claimed in my copendingpatent application Ser. No. 550,470, filed Dec. 1, 1955. As a telephonecable splice the capsule may advantageously be about 2% inches in lengthand about inch internal diameter, and the plug may be about /2 inch inlength with an outside diameter substantially the same as the internaldiameter of the capsule.

In making the splice, the stripped ends of the insulated conductors aretwisted to make an effective conducting contact, and the insulated endportions of the conductors are positioned in the grooves 11 of the plug6 as hereinbefore described with the inner end of the plug spaced aboutinch from the adjacent twisted stripped ends (7) of the conductors. Thecapsule 5 is filled to within about inch of its open end with theputty-like plastic composition 8. This composition is the reactionproduct resulting from heating to a temperature within the range of 200to 400 F. a mixture made up essentially of 30 to 50% by weight ofmineral oil, 2 to 7% by weight of polyisobutylene having a molecularweight between 50,000 and 150,000, 15 to 20% by Weight of polyethyleneand 30 to 40% of methylated paralfin; more fully described in myaforementioned patent application. The plug 6 is inserted in the openend of the capsule and into ramming contact with the plastic composition8 to force the composition around the splice.

The plug 6 functions as a plunger, separator and stopper. After the plughas been inserted in the capsule and makes contact with the compositiontherein, it acts as a plunger or ram to force the composition around thetwisted stripped ends of the conductors and between and around the shortunstripped portions of the conductors adjacent the plug and beyond thegrooves 11. The plug serves to separate the short unstripped portions ofthe conductors within the capsule, thus allowing clearance for thecomposition to get between the conductors and encase them. When allportions of the conductors within the capsule are completely surroundedby and embedded in the composition, the plug serves as a stopper tomaintain the parts within the capsule securely in position.

Fig. 3 of the drawing shows an insulated telephone through cable 12 withthree splices of the invention (indicated by the capsules 5) connectingindividual insulated conductors (e.g. 1010') of the cable to individualinsulated conductors (cg. 9) of an insulated bridge cable 13. Thesplices and the exposed portions of the individual insulated conductorsof both the through and bridge cables are covered by a wrapping offriction tape 14 which in turn is enclosed in a Waterproof cablejunction enclosure. Essentially, the junction enclosure comprises twoplastic cylindrical collars 15 and (e.g. 0.02 inch greater) than thediameter of the through cable. Similarly, the mating halves of thecollar 16 have two mating openings 20 and 21 parallel to the axis and ofjust slightly greater diameter than the diameters of the through andbridge cables, respectively, and two transverse mating bolt holes 22.

The junction enclosure is assembled by bolting together the two matinghalves of the collars 15 and 16 with the cables 12 and 13 extendingthrough their respective openings and the tape-wrapped splices betweenthe two collars. Each of the cable openings 18, 2G and 21 has,intermediate the ends of its collar, a slight recess (e.g. 23 in collar15) which is filled with the aforementioned plastic composition prior toassembly of the collar halves and cables. The outside cylindricalsurfaces of the collars are smeared with the aforementioned plasticcomposition of low viscosity and a sheet of plastic 23 mayadvantageously be about 0.06 inch, they may terminate /8 inch short ofeach end of the collar, and be initially filled with the composition toa depth at least 0.02 inch greater than the depth of the recess. The

edges of the tube around the collars are provided with an application ofthe plastic composition 25, and the assembly is finally covered with oneor more alternating layers of a weatherproofing compound 26 and frictiontape 27.

The splice of the invention is of particular advantage with conductorsinsulated with polyethylene and the plastic insulating composition of myaforesaid patent application. The surface of polyethylene is of a waxynature, and the plastic insulating composition possesses theadvantageous property of remarkably strong adherence to polyethylene.Thus, a practically perfect bond is attained between the conductorinsulation and the composition. The composition also adheres strongly toother plastics, to metal, rubber, wood, etc., so that practicallyperfect bonds are attained between the composition and the inside wallof the capsule, the inner face of the plug and the twisted stripped endsof the conductors.

Splices made in accordance with the invention (Fig. 1) have beenimmersed in water at room temperature and at 50 C. for many weeks (testsdiscontinued) without evidencing any failures. A failure constitutes aninternal resistance reading less than infinite. Similarly the cablejunction enclosure (Fig. 3) has been immersed in water at 50 C. forindefinite periods of time with no evidence of water within theenclosure.

' I claim:

1. In a splice for an insulated electric conductor, the improvementwhich comprises a cylindrical capsule having one end closed and theother end open, a cylindrical plug securely fitted within and forming astopper for the capsule near its open end, said plug having a pluralityof circumferentially spaced peripheral grooves extending longitudinallyalong its cylindrical surface, an insulated electric conductor extendingthrough each of said grooves into said capsule, the ends of saidconductors within the capsule being stripped of insulation up to a shortdistance from the inner face of the plug, whereby insulation is retainedon each conductor for said short distance beyond the inner face of theplug, the unstripped portion of the conductors within the capsule beingheld separated by said plug, the stripped ends of said conductors beingtwisted into effective electrical contact, and a plastic insulatingcomposition completely filling said capsule between its closed end andsaid plug, completely surrounding and embedding the twisted strippedends and the aforesaid short insulated lengths of the conductors withinthe capsule, and closing the ends of the grooves around the conductorsand the space between the periphery of the plug and the inner end of thecapsule at the inner end of the plug to form a watertight seal.

2. The improvement according to claim 1 in which the capsule is made ofcellulose acetate butyrate.

3. The improvement according to claim 1 in which the plastic insulatingcomposition is the reaction product resulting from heating a mixturemade up essentially of mineral oil, polyisobutylene, polyethylene andmethylated paraffin.

4. The improvement according to claim 3 in which at least the outerinsulation of the conductors consists essentially of polyethylene.

5. The improvement according to claim 1 in which the short insulatedportions of the conductors within the capsule converge abruptly from thegrooves to the twisted stripped ends thereof and the space between theinner face of the plug and the adjacent twisted stripped ends of theconductors is about one-fourth of an inch.

6. In a cable junction enclosure, a plurality of splices electricallyconnecting individual-insulated electric conductors of a through cableto individual insulated electric conductors of a bridge cable, each ofsaid splices comprising a cylindrical capsule having one end closed andthe other end open, a cylindrical plug securely fitted within andforming a stopper for the capsule near its open end, said plug having aplurality of circumferentially spaced peripheral grooves extendinglongitudinally along its cylindrical surface, an insulated conductorextending through each of said grooves into said capsule, the ends ofsaid conductors within the capsule being stripped of insulation up to ashort distance from the inner face of the plug, whereby insulation isretained on each conductor for said short distance beyond the inner faceof the plug, the unstripped portion of the conductors within the capsulebeing held separated by said plug, the stripped ends being twisted intoelfective electrical contact, and a plastic insulating compositioncompletely filling said capsule between its closed end and said plug,completely surrounding and embedding the twisted stripped ends and theaforesaid short insulated lengths of the conductors within the capsuleand closing the ends of the grooves around the conductors and the spacebetween the periphery of the plug and the inner end of the capsule atthe inner end of the plug to form a watertight seal, and a waterproofenclosure for said splices comprising a cylindrical tube of aninsulating plastic surrounding said plurality of splices and closed atits opposite ends by cylindrical collars each inserted therewithin andextending a short distance beyond the adjacent end of the tube, each ofsaid collars consisting of two mated half cylinders secured together andhaving a longitudinal opening through which the through cable extends,one of said collars having another longitudinal opening through whichthe bridge cable extends, and a waterproofing compound surrounding thetube and the exposed ends of said collars in adherence therewith.

7. The enclosure according to claim 6, further characterized in thateach of the longitudinal cable openings in said collars has a recessintermediate the ends of the collars, and a plastic insulatingcomposition filling each of sa d ?9Sses.

, (References on following page) 5 References Cited in the file of thispatent 2,621,228 UNITED STATES PATENTS 5; 997,066 Krannichfeldt July 4,1911 1,297,614 Van Viersen U Mar. 18, 1919 5 1,896,581 Hagedorn et a1.Feb. 7, 1933 823 809 1,933,555 Jasper Nov. 7, 1933 495127 2,576,227Hutchins Nov. 27, 1951 6 Tompers Dec. 9, 1952 Netherwood Apr. 7, 1953Kozacka et a1. June 15, 1954 FOREIGN PATENTS France Oct. 25, 1937 GreatBritain Nov. 8, 1938

